The 25-year-old star, who ended his romance with Campbell, 22, after 14 months of dating, is said to have sought comfort from his ex lover, who he dated for four years, reported Femalefirst.
"Louis has had a rough ride the past few months and Eleanor wants him to know she is there if he needs anybody to talk to. They were together for a number of years and Louis feels he can rely on her," a source said.
However, Tomlinson, who has 12-month-old son Freddie with ex partner Briana Jungwirth, is said to have vowed to maintain a friendship with Campbell.